Some prior patents on metallized envelopes for protection of electronic components are U.S. Pat. No. 4,154,344 (Parent) and U.S. Pat. No. 4,156,751 (Divisional), both issued to Yenni et al, assignors to 3M. Both patents relate to envelopes having an inside antistatic surface with a surface resistivity of 10.sup.8 to 10.sup.14 ohms/square, a core insulative sheet with a volume resistivity of at least 10.sup.10 ohm-centimeters, and an outside metal conductive surface with a surface resistivity not greater than 10.sup.4 ohms/square. The 3M patents and the publicly available file histories thereof teach this outside surface has a surface resistivity of no greater than 10.sup.4 even if there is a polymeric abrasion protection coating on the metal. For instance, 3M's commercially available 2100 bag has from bag outside to bag inside the structure: nickel/insulative polyester/adhesive/antistatic film of LDPE containing antistat. (The patents say the antistat is Ampacet No. 10069.) The nickel bag outside is coated with an ultrathin polymeric abrasion protection coating and still at ambient humidity and temperature the 2100 bag exhibits on the nickel outside a surface resistivity of 10.sup.4 ohms/square. Such bags are referred to as "metal out".
Also of interest is U.S. Pat. No. 4,756,414 issued in 1988 to Mott, assignor to Dow Chemical. This patent relates to a bag or pouch having a first and second antistatic layer, which antistat layers are the electron beam radiation cured product as taught by British Published patent application 2,156,362 (which is the counterpart of U.S. Pat. No. 4,623,594 issued November 18, 1986 to Keough, assignor to Metallized Products). This electron beam radiation cured antistat film is sold by Metallized Products under the registered trademark Staticure. As per '414, these antistatic layers are bonded along their primary surfaces so that the secondary antistatic surface of one will form the bag outside and the secondary antistatic surface of the other will form the bag inside. At least one primary surface has on it a metal conductive layer, which then due to the sandwiching structure is an internal core of the bag layers. Commercial products like this are referred to as "metal in". For instance, a "metal in" structure is Dow's commercial Chiploc-ES bag, which from the bag outside to the bag inside is of the structure: Staticure/insulative polyester/metal/Staticure /LDPE. Another commercial "metal in" structure is what Fujimori sells as their NONSTAT-PC bag, which from the bag outside to the bag inside is of the structure: antistatic layer/insulative polyester/metal/antistatic layer.
Also of interest is U.S. Pat. No. 4,407,872 issued in 1983 to Horii, assignor to Reiko. This patent relates to an envelope for packaging electronic parts, the envelope having an outside layer of plastic and an inner metal film layer, the metal layer having electrical resistance less than 10.sup.8 ohms/square centimeter. Optionally on the envelope inside is a heat-sealable resin film layer laminated onto the metal film layer. This also creates a "metal in" sandwich of the structure: plastic layer/metal layer/heat sealing layer.